1. Field of the Invention
The present invention relates to a developing apparatus and method thereof for performing developing processing for, for example, substrates.
2. Description of the Related Art
A mask for forming a predetermined pattern on a top surface of a glass substrate (LCD substrate) of a liquid crystal display or a semiconductor wafer (hereinafter referred to as "a wafer" ) is obtained by applying a resist onto a top surface of a substrate such as a wafer, thereafter applying light, electron beams, ionic beams or the like, to the resist surface, and performing development.
The developing processing here is performed by dissolving the portions to which light or the like has been radiated or the portions without such radiation with use of an alkaline solution or the like, and is conventionally performed, for example, as follows. Initially, as shown in FIG. 25A, a substrate, for example, a wafer W is vacuum-held on a spin chuck 10 having, for example, a vacuum-suction function, and a bar-shaped supply nozzle 11 having a number of discharging apertures is disposed above a center portion of the wafer W. Then as shown in FIG. 25B, the wafer is rotated 180 degrees while a developing solution D is supplied onto the top surface of the wafer from the supply nozzle 11, and thereby the developing solution D is heaped on the resist film. Subsequently, as shown in FIG. 25 C, after the wafer W is left standing for 60 seconds with the rotation of the wafer W being stopped, a rinse solution is supplied onto the top surface of the wafer to remove the developing solution, and thus the development is performed.
Though the developing solution D is controlled at a temperature of, for example, about 23.degree. C., water contained in the developing solution D vaporizes while the wafer W and is left standing with the solution-heaping being performed, thereby depriving the latent heat of the developing solution D, and as a result, the temperature of the developing solution D decreases with time as shown in FIG. 26.
Meanwhile, the spin chuck 10 for holding an area close to a center of the wafer W has some dimensions, since it vertically moves, and rotates, while holding the wafer W. The spin chuck 10 is maintained at the temperature of, for example, about 23.degree. C. by, for example, temperature-adjusting water so that the influence of the temperature from a motor not illustrated for driving the spin chuck 10 is eliminated. Accordingly, the spin chuck 10 has a large thermal capacity, which brings about the difference in the degree of the temperature reduction of the developing solution D between the portion of the wafer W in contact with the spin chuck 10 and the portion not in contact therewith, and thus the temperature of the area close to the center of the wafer does not easily decrease compared with that of a peripheral portion.
Consequently, the temperature difference in the developing solution D of about 1.degree. C. occurs between the area close to the center and the peripheral portion of the wafer at the time of starting rinse. When such temperature distribution occurs on the wafer, the temperature difference in the developing solution D has an effect on the progress of the development, thus bringing about an uneven sate of development and causing a disadvantage of varying the finished dimensions. In concrete, with use of an I beam resist, if the temperature difference is 1.degree.C., line width differs by about 4 nm, and thus if the line width in the area close to the center of the wafer is about 0.4 micrometers, the line width in the peripheral portion becomes about 0.396 micrometers.